/*---------------------------------------
   MULTI2.C -- Multitasking Demo
               (c) Charles Petzold, 1996
  ---------------------------------------*/

#include <windows.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <process.h>

typedef struct
     {
     HWND hwnd ;
     int  cxClient ;
     int  cyClient ;
     int  cyChar ;
     BOOL bKill ;
     }
     PARAMS, *PPARAMS ;

LRESULT APIENTRY WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
                    PSTR szCmdLine, int iCmdShow)
     {
     static char szAppName[] = "Multi2" ;
     HWND        hwnd ;
     MSG         msg ;
     WNDCLASSEX  wndclass ;

     wndclass.cbSize        = sizeof (wndclass) ;
     wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
     wndclass.lpfnWndProc   = WndProc ;
     wndclass.cbClsExtra    = 0 ;
     wndclass.cbWndExtra    = 0 ;
     wndclass.hInstance     = hInstance ;
     wndclass.hIcon         = LoadIcon (NULL, IDI_APPLICATION) ;
     wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
     wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
     wndclass.lpszMenuName  = NULL ;
     wndclass.lpszClassName = szAppName ;
     wndclass.hIconSm       = LoadIcon (NULL, IDI_APPLICATION) ;

     RegisterClassEx (&wndclass) ;

     hwnd = CreateWindow (szAppName, "Multitasking Demo",
                          WS_OVERLAPPEDWINDOW,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          NULL, NULL, hInstance, NULL) ;

     ShowWindow (hwnd, iCmdShow) ;
     UpdateWindow (hwnd) ;

     while (GetMessage (&msg, NULL, 0, 0))
          {
          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
          }
     return msg.wParam ;
     }

int CheckBottom (HWND hwnd, int cyClient, int cyChar, int iLine)
     {
     if (iLine * cyChar + cyChar > cyClient)
          {
          InvalidateRect (hwnd, NULL, TRUE) ;
          UpdateWindow (hwnd) ;
          iLine = 0 ;
          }
     return iLine ;
     }

// Window 1: Display increasing sequence of numbers
// ------------------------------------------------

void Thread1 (PVOID pvoid)
     {
     int     iNum = 0, iLine = 0 ;
     char    szBuffer[16] ;
     HDC     hdc ;
     PPARAMS pparams ;

     pparams = (PPARAMS) pvoid ;

     while (!pparams->bKill)
          {
          if (iNum < 0)
               iNum = 0 ;

          iLine = CheckBottom (pparams->hwnd,   pparams->cyClient,
                               pparams->cyChar, iLine) ;

          wsprintf (szBuffer, "%d", iNum++) ;

          hdc = GetDC (pparams->hwnd) ;

          TextOut (hdc, 0, iLine * pparams->cyChar,
                   szBuffer, strlen (szBuffer)) ;

          ReleaseDC (pparams->hwnd, hdc) ;

          iLine++ ;
          }
     _endthread () ;
     }

LRESULT APIENTRY WndProc1 (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
     {
     static PARAMS params ;

     switch (iMsg)
          {
          case WM_CREATE :
               params.hwnd = hwnd ;
               params.cyChar = HIWORD (GetDialogBaseUnits ()) ;
               _beginthread (Thread1, 0, &params) ;
               return 0 ;

          case WM_SIZE :
               params.cyClient = HIWORD (lParam) ;
               return 0 ;

          case WM_DESTROY :
               params.bKill = TRUE ;
               return 0 ;
          }
     return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
     }

// Window 2: Display increasing sequence of prime numbers
// ------------------------------------------------------

void Thread2 (PVOID pvoid)
     {
     char    szBuffer[16] ;
     int     iNum = 1, iLine = 0, i, iSqrt ;
     HDC     hdc ;
     PPARAMS pparams ;

     pparams = (PPARAMS) pvoid ;

     while (!pparams->bKill)
          {
          do
               {
               if (++iNum < 0)
                    iNum = 0 ;

               iSqrt = (int) sqrt (iNum) ;

               for (i = 2 ; i <= iSqrt ; i++)
                    if (iNum % i == 0)
                         break ;
               }
          while (i <= iSqrt) ;

          iLine = CheckBottom (pparams->hwnd,   pparams->cyClient,
                               pparams->cyChar, iLine) ;

          wsprintf (szBuffer, "%d", iNum) ;

          hdc = GetDC (pparams->hwnd) ;

          TextOut (hdc, 0, iLine * pparams->cyChar,
                   szBuffer, strlen (szBuffer)) ;

          ReleaseDC (pparams->hwnd, hdc) ;

          iLine++ ;
          }
     _endthread () ;
     }

LRESULT APIENTRY WndProc2 (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
     {
     static PARAMS params ;

     switch (iMsg)
          {
          case WM_CREATE :
               params.hwnd = hwnd ;
               params.cyChar = HIWORD (GetDialogBaseUnits ()) ;
               _beginthread (Thread2, 0, &params) ;
               return 0 ;

          case WM_SIZE :
               params.cyClient = HIWORD (lParam) ;
               return 0 ;

          case WM_DESTROY :
               params.bKill = TRUE ;
               return 0 ;
          }
     return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
     }

// Window 3: Display increasing sequence of Fibonacci numbers
// ----------------------------------------------------------

void Thread3 (PVOID pvoid)
     {
     char    szBuffer[16] ;
     int     iNum = 0, iNext = 1, iLine = 0, iTemp ;
     HDC     hdc ;
     PPARAMS pparams ;

     pparams = (PPARAMS) pvoid ;

     while (!pparams->bKill)
          {
          if (iNum < 0)
               {
               iNum  = 0 ;
               iNext = 1 ;
               }

          iLine = CheckBottom (pparams->hwnd,   pparams->cyClient,
                               pparams->cyChar, iLine) ;

          wsprintf (szBuffer, "%d", iNum) ;

          hdc = GetDC (pparams->hwnd) ;

          TextOut (hdc, 0, iLine * pparams->cyChar,
                   szBuffer, strlen (szBuffer)) ;

          ReleaseDC (pparams->hwnd, hdc) ;

          iTemp  = iNum ;
          iNum   = iNext ;
          iNext += iTemp ;

          iLine++ ;
          }
     _endthread () ;
     }

LRESULT APIENTRY WndProc3 (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
     {
     static PARAMS params ;

     switch (iMsg)
          {
          case WM_CREATE :
               params.hwnd = hwnd ;
               params.cyChar = HIWORD (GetDialogBaseUnits ()) ;
               _beginthread (Thread3, 0, &params) ;
               return 0 ;

          case WM_SIZE :
               params.cyClient = HIWORD (lParam) ;
               return 0 ;

          case WM_DESTROY :
               params.bKill = TRUE ;
               return 0 ;
          }
     return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
     }

// Window 4: Display circles of random radii
// -----------------------------------------

void Thread4 (PVOID pvoid)
     {
     HDC     hdc ;
     int     iDiameter ;
     PPARAMS pparams ;

     pparams = (PPARAMS) pvoid ;

     while (!pparams->bKill)
          {
          InvalidateRect (pparams->hwnd, NULL, TRUE) ;
          UpdateWindow (pparams->hwnd) ;

          iDiameter = rand() % (max (1,
                                min (pparams->cxClient, pparams->cyClient))) ;

          hdc = GetDC (pparams->hwnd) ;

          Ellipse (hdc, (pparams->cxClient - iDiameter) / 2,
                        (pparams->cyClient - iDiameter) / 2,
                        (pparams->cxClient + iDiameter) / 2,
                        (pparams->cyClient + iDiameter) / 2) ;

          ReleaseDC (pparams->hwnd, hdc) ;
          }
     _endthread () ;
     }

LRESULT APIENTRY WndProc4 (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
     {
     static PARAMS params ;

     switch (iMsg)
          {
          case WM_CREATE :
               params.hwnd = hwnd ;
               params.cyChar = HIWORD (GetDialogBaseUnits ()) ;
               _beginthread (Thread4, 0, &params) ;
               return 0 ;

          case WM_SIZE :
               params.cxClient = LOWORD (lParam) ;
               params.cyClient = HIWORD (lParam) ;
               return 0 ;

          case WM_DESTROY :
               params.bKill = TRUE ;
               return 0 ;
          }
     return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
     }

// Main window to create child windows
// -----------------------------------

LRESULT APIENTRY WndProc (HWND hwnd, UINT iMsg, WPARAM wParam, LPARAM lParam)
     {
     static char   *szChildClass[] = { "Child1", "Child2",
                                       "Child3", "Child4" } ;
     static HWND    hwndChild[4] ;
     static WNDPROC ChildProc[] = { WndProc1, WndProc2,
                                    WndProc3, WndProc4 } ;
     HINSTANCE      hInstance ;
     int            i, cxClient, cyClient ;
     WNDCLASSEX     wndclass ;

     switch (iMsg)
          {
          case WM_CREATE :
               hInstance = (HINSTANCE) GetWindowLong (hwnd, GWL_HINSTANCE) ;

               wndclass.cbSize        = sizeof (wndclass) ;
               wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
               wndclass.cbClsExtra    = 0 ;
               wndclass.cbWndExtra    = 0 ;
               wndclass.hInstance     = hInstance ;
               wndclass.hIcon         = NULL ;
               wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
               wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
               wndclass.lpszMenuName  = NULL ;
               wndclass.hIconSm       = NULL ;

               for (i = 0 ; i < 4 ; i++)
                    {
                    wndclass.lpfnWndProc   = ChildProc[i] ;
                    wndclass.lpszClassName = szChildClass[i] ;

                    RegisterClassEx (&wndclass) ;

                    hwndChild[i] = CreateWindow (szChildClass[i], NULL,
                          WS_CHILDWINDOW | WS_BORDER | WS_VISIBLE,
                          0, 0, 0, 0, hwnd, (HMENU) i, hInstance, NULL) ;
                    }

               return 0 ;

          case WM_SIZE :
               cxClient = LOWORD (lParam) ;
               cyClient = HIWORD (lParam) ;

               for (i = 0 ; i < 4 ; i++)
                    MoveWindow (hwndChild[i], (i % 2) * cxClient / 2,
                                              (i > 1) * cyClient / 2,
                                cxClient / 2, cyClient / 2, TRUE) ;
               return 0 ;

          case WM_CHAR :
               if (wParam == '\x1B')
                    DestroyWindow (hwnd) ;

               return 0 ;

          case WM_DESTROY :
               PostQuitMessage (0) ;
               return 0 ;
          }
     return DefWindowProc (hwnd, iMsg, wParam, lParam) ;
     }
